CC_FOR_TARGET in libctf Makefile

[Alan Modra]

On Fri, Feb 19, 2021 at 01:52:16PM +0000, Nick Alcock wrote:
> On 19 Feb 2021, Alan Modra outgrape:
> 
> > Nick,
> > What is CC_FOR_TARGET doing in the libctf Makefile?  That seems wrong
> > to me.  You aren't building or testing libctf for the target.  You are
> > building it for the host!
> 
> Ugh yes that's completely true. I mixed up host and target when figuring
> out what I needed to build and run the lookup tests. The lookup tests
> rely on compiling (and linking) test "input" programs for the target and
> running the lookup program on them, but the lookup program is still a
> host program and run on the host.
> 
> >                            I see this in my build dir libctf Makefile
> > on x86_64:
> >
> > CC_FOR_TARGET = ` \
> > ...
> >     if [ "x86_64-pc-linux-gnu" = "@target@" ] ; then \
> 
> Well, we do need potentially two C compilers -- the build compiler (to
> compile the actual things we're testing for the host) and the host
> compiler (in non-ctf-writable/ tests, to compile programs containing CTF
> for the target, though we only peek inside them with the lookup
> programs, we don't run them.)
> 
> I thought CC_FOR_TARGET was the way to get the latter of these. Was I
> wrong?

Huh, I suppose you do need CC_FOR_TARGET then.  Which means
AC_CANONICAL_TARGET is needed.

> > So no substitution of @target@ due to lack of AC_CANONICAL_TARGET in
> > the libctf configure.ac.  That's not to say I think you should add
> > AC_CANONICAL_TARGET, I think CC_FOR_TARGET should disappear.
> 
> Not so sure about that, though you're right I need to do *something*.
> 
> -- 
> NULL && (void)

-- 
Alan Modra
Australia Development Lab, IBM